Utility poles are often made from wood treated with one or more preservatives such as creosote. Wooden utility poles are often desirable since they are less expensive and readily obtainable compared to poles made from metal or composite materials. Although the wooden utility poles are treated with a preservative, these poles are often subject to decay and insect damage. Since the wood preservative does not always penetrate the center of the wooden pole, the center is prone to decomposition near or below the ground line. As the pole continues to decompose, its structural integrity is weakened and the pole eventually must be repaired or replaced.
It is generally desirable to repair and strengthen a damaged utility pole rather than replace the entire pole. The replacement of utility poles is time consuming and expensive. Furthermore, when a utility pole is replaced, it is necessary to interrupt power or telephone service, thereby inconveniencing the utility customers. Heavy equipment and skilled workers are also required to replace a utility pole.
It is thus desirable to repair or strengthen a utility pole in situ whenever possible. Numerous methods and devices have been proposed in the past for repairing poles without removing the pole from the ground. One prior method of repairing damaged utility poles is to excavate around the pole, remove the decomposed material from the pole and helically wind a rubber strip around the damaged area. A sleeve is then placed around the pole and a hardenable composition poured between the pole and the sleeve. One example of this type of process is disclosed in U.S. Pat. No. 4,892,601 to Norwood. This process relies primarily on the strength of the hardenable material for the reinforcing strength to the pole. Furthermore, this process is time consuming by requiring the assembly of the sleeve around the pole and removing the sleeve after the composition has hardened.
Other methods of repairing and reinforcing utility poles comprise removing the ground around the damaged area of the utility pole and applying a reinforcing material around the damaged area. The reinforcing material is usually saturated with a resin, such as a polyester or epoxy resin, which when cured, provides sufficient strength to the reinforcing material. Examples of this type of repair method are disclosed in U.S. Pat. No. 4,921,555 to Skiff; U.S. Pat. No. 4,918,883 to Owen et al.; U.S. Pat. No. 5,027,575 to Owen et al.; and U.S. Pat. No. 2,109,508 to Schmittutz.
These previous methods of repairing and reinforcing utility poles suffer from several disadvantages. For example, many of these methods require the reinforcing material to be saturated with a resinous material before applying the reinforcing material to the damaged area. These saturated reinforcing materials are typically difficult to handle and apply to the damaged area. In addition, many of these methods use combustible resinous materials, and thus, do not provide any fire protection to the wooden utility pole. In areas where brush fires occur regularly, it is desirable to repair damaged utility poles With a non-combustible material. Many methods use resins that are sensitive to ultraviolet radiation, and thus, have a limited life or require additional coating to provide UV protection.